US20040055873A1

US20040055873A1 - Apparatus and method for improved electroforming

Info

Publication number: US20040055873A1
Application number: US10/249,718
Authority: US
Inventors: Alex Greenspan
Original assignee: Digital Matrix
Current assignee: Digital Matrix
Priority date: 2002-09-24
Filing date: 2003-05-02
Publication date: 2004-03-25
Also published as: CN2695454Y

Abstract

The present invention includes an apparatus and method for providing optimal uniformity of deposition during an electroplating process. The system may include an agitating device which is configured to provide agitation to the anode basket, a bias current distributed over a control grid (e.g., titanium mesh) which is disposed between the anode and cathode, wherein the control grid is configured to substantially reduce the variation in the electric field across the cathode, a cathode which includes a backplate having a contact ring wherein the contact ring includes a device configured to increase the pressure of the contact ring against the backplate and/or a cathode mounted on a lead screw for providing axial movement of the cathode along an axis normal to the anode.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and the benefit of, U.S. Provisional Patent Application Serial No. 60/413,083, filed on Sep. 24, 2002, the entire contents of which is hereby incorporated by reference.[0001]

TECHNICAL FIELD OF THE INVENTION

This invention generally relates to an apparatus and method for reliable, efficient, cost effective and repeatable electroforming of a master, and more particularly, to an apparatus and method for facilitating the uniformity of deposition.

BACKGROUND OF THE INVENTION

Electroforming generally involves the electrochemical deposition of a layer of metal or alloy from a suitable electrolyte solution onto a pattern usually comprised of a thin layer of metal substrate. More particularly, the article to be plated (“master”) is typically connected to a cathode and rotated in a cell. An anode is also typically located in the cell and usually consists of a basket containing the metal to be deposited. The cell also commonly contains an electrolytic (plating) solution which most often forms a conductive path between the basket and the part to be plated. Using this configuration, as sufficient direct current flows through the anode, metallic ions are typically pulled from the electrolytic solution surrounding the cathode and are deposited onto the part connected to the cathode. As the process continues, the deposited plating layer typically increases in thickness, while the material in the anode basket replenishes the metallic ions in the electrolytic solution.

The aforementioned plating process is typically used to produce a die (“stamper”, “matrix”or “father”) for injection molding of various products including, inter alia, optical discs. The stamper is typically formed (“grown”) on a metalized glass master which serves as the mandrel. In preparation for optical disc manufacturing, the surface of the glass master contains microscopic pits of varying lengths in a spiral pattern. Optimally, the surface features of the stamper are an inverse duplicate of the pits on the original glass master. Due to the need for extreme accuracy in duplicating these microscopic pits during the manufacture of optical disc media, it is often critical to strictly maintain the precision of the plating process.

To achieve these optimal results, the stamper is typically manufactured with a uniform thickness. Stampers typically have a nominal thickness of 290 microns (0.290 mm)+/−3 microns, such that the thickness of the stamper does not vary by more than 6 microns. However, with market demands for new higher density formats for optical discs, the thickness variation tolerance most likely will require a decreased thickness variation of +/−1 microns. To obtain a decreased thickness variation for the high density stamper, an overall increased precision in many aspects of the electroforming process will be required.

The thickness variation across the surface of the stamper is partly dependent upon the distance between the cathode and anode in the electroforming device. Even though the amount of overall metal typically remains constant, the thickness profile will usually vary according to the anode/cathode distance. When a cathode is moved closer to the anode, increased deposition often occurs in the center of the stamper. Conversely, with increased distance between the cathode and anode, the thickness in the center of the stamper is often reduced. Thus, an optimal orientation of the cathode to anode distance would, in an exemplary embodiment, result in a minimal thickness variation from the center of the stamper to the edge of the stamper. However, a predetermined setting for the anode/cathode distance typically does not guarantee uniform thickness because many other factors often contribute to thickness variations, i.e. fixturing device, size of baffle opening, temperature and pH.

Currently in the industry, electroforming equipment often provides either for no adjustment between the anode and cathode or for crude and course methods for changing the distance between the anode and cathode. For example, adjusting the distance between the anode and cathode by moving the anode basket is often impractical due to the weight of the basket when filled with the raw metals. Moreover, prior art devices which allow for the replacement of the cathode shaft with a cathode shaft of a differing length do not provide continuous adjustability and often require extra labor and excess expensive parts. Therefore, an apparatus and method for efficiently varying the distance between the anode and cathode to compensate for varying parameters.

As discussed above, a stamper is typically formed on a glass master because of the ionic attraction between the anode and cathode. The ionic attraction is developed from an electrical contact on the surface of the glass master. Because the front surface of the glass master is usually the only surface that is metalized, the metalized surface is typically the only point for the electrical contact. However, to prevent damage to the data which is closer to the center of the master, the electrical contact should, in an exemplary embodiment, avoid contact with the center of the master. Fortunately, ample space typically exists for making an electrical contact on the front surface of the master because the standard industry glass master is 120 mm in radius while the information area only extends from the center of the master out to a radius of about 60 mm.

The metalized layer which forms the electrical contact on the surface of the glass master is typically very thin, i.e. approximately 600 angstroms. To pass high current through this thin layer, a very low initial current is typically used, then the current is increased gradually until the metalized layer is built up by the newly deposited metal ions from the electrolytic solution. Building up the metalized layer of the glass master with the metal deposits is often critical because any portions of the glass master which are not plated will usually burn when the current ramps up. Thus, not only is the inner information area of the master plated, but the outer area which serves as the electrical contact is also typically plated. Plating the outside area which serves as the electrical contact usually results in part of the fixture being unintentionally plated. Plating deposits on the fixture is often undesirable because of the extra maintenance required to remove the plating from the fixture and the adverse affects on thickness variation.

A fixture which sufficiently seals off metal parts from the build-up of plating during the plating operation is needed. A non-metallic material is needed which is both compatible with the plating bath and includes adequate mechanical properties. Prior art clamping rings typically include a circular disc with a threaded rim which is threadedly received into the backplate. Threaded fittings are problematic because of variations in the torque applied by individual operators when rotating the clamping ring, thereby resulting in an unequal seal applied around the ring, difficulty in obtaining repeatable compression and variations in the overall contact pressure against the sides of the clamping ring. These prior art clamping rings are typically constructed of a plastic material which is not sufficiently rigid to provide an adequate seal. To obtain an adequate seal, the material should be rigid, but not brittle. Most often, CPVC or polypropylene are used for this process; however, both of these materials are somewhat soft and not dimensionally stable at the temperatures required, i.e. 20-65Â° C. Furthermore, seals on currently available fixtures typically leak and often require substantial maintenance. A fixture with increased performance, less maintenance and easier on and off loading is needed in the electroforming industry.

Moreover, most electroforming systems designed for producing optical disc stampers utilize a rotary cathode head and a stationary anode basket. The arrangement allows the metalized master to rotate with respect to the anode basket while the nickel plating occurs and the stamper grows. The rotation of the cathodic master typically includes the benefit of causing agitation of the solution, and helping to smooth out irregularities in the thickness of deposition of nickel. These irregularities are caused by irregularities in the electric field, which are in turn caused by unevenness in the geometry of the anode basket with respect to the cathodic master. If the anode basket and cathode could be perfectly parallel to each other, then the thickness variation would be much improved. Since the anode basket typically contains nickel anode pellets, which are almost constantly corroding as a necessary part of the process, it is not practical to expect perfect geometry on a continuous basis. Further, the sludge created by the corroding anodes adds to the inconsistency of the anode basket and causes unevenness in the electric field. Additionally, because the nickel anodes are typically continuously corroding within the anode basket, it is important to sufficiently pack and clean the anodes to maintain optimal thickness variation. If the anodes are not sufficiently packed and cleaned, voids and sludge build-up within the basket may have an adverse effect on the thickness variation due to the effect on the electrical field. More details related to electroforming devices may be found in U.S. Pat. Nos. 5,785,826 and 5,843,296 which are attached hereto and incorporated herein by reference.

SUMMARY OF INVENTION

The present invention includes an apparatus and method for providing optimal uniformity of deposition during an electroplating process. The system may include an agitating device which is configured to provide agitation to the anode basket, a bias current distributed over a control grid (e.g., titanium mesh) which is disposed between the anode and cathode, wherein the control grid is configured to substantially reduce the variation in the electric field across the cathode, a cathode which includes a backplate having a contact ring wherein the contact ring includes a device configured to increase the pressure of the contact ring against the backplate and/or a cathode mounted on a lead screw for providing axial movement of the cathode along an axis normal to the anode. The entire cathode head may be mounted on a lead screw which, when manually turned, moves the cathode head in or out in relation to the anode basket. Alternatively, the lead screw is driven by a servo motor which is controlled by a computer.

BRIEF DESCRIPTION OF DRAWINGS

Exemplary embodiments of the present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like numerals denote like elements and: [0013]
FIG. 1 shows an exemplary electroforming apparatus in accordance with the present invention; [0014]
FIG. 2 shows an exemplary cathode assembly in accordance with the present invention; [0015]
FIG. 3 shows an exemplary backplate in accordance with the present invention; [0016]
FIG. 4[0017] a shows an exemplary backplate 40 for creating a “father”from a glass master in accordance with the present invention;
FIG. 4[0018] b shows an exemplary backplate 40 for creating a “mother”from a “father”in accordance with the present invention;
FIG. 4[0019] c shows an exemplary backplate 40 for creating a stamper from a “mother”in accordance with the present invention;
FIG. 5 shows a detailed view of an exemplary contact ring incorporated into a backplate; [0020]
FIG. 6 shows an exemplary electroplating device with the location of the cathode and anode exchanged; [0021]
FIG. 7 shows an exemplary electroplating device having a vibration motor interfaced with the anode basket; [0022]
FIG. 8 shows an exemplary electroplating device having a titanium mesh disposed between a stationary cathode and anode basket; [0023]
FIG. 9 shows a more detailed view of an exemplary electroplating device having a titanium mesh disposed between a stationary cathode and anode basket; [0024]
FIG. 10 shows a detailed view of the exemplary circuitry that allows for the adjustment of the bias current on the titanium control mesh which is disposed between a stationary cathode and anode basket; and, [0025]
FIG. 11 shows an exemplary contact ring having exemplary spring elements.[0026]

DETAILED DESCRIPTION

Referring to FIG. 1, an apparatus and method according to various aspects of the present invention is suitably configured to continuously adjust the anode [0027] 17-to-cathode 20 distance thereby controlling uniformity of deposition. With momentary reference to FIG. 3, the apparatus and method according to various aspects of the present invention is also suitably configured for providing a hinged, coated, metal clamping mechanism for efficiently fixturing a master into a backplate 40. While the manner in which the electroforming is accomplished is described in greater detail below, in general with reference to FIGS. 1 and 3, clamping ring 42 secures master 90 onto backplate 40, then screw 24 adjusts cathode assembly 20 to an optimal distance from anode basket 17 in preparation for the electroforming process.
With continued reference to FIG. 1, [0028] electroforming device 10, in an exemplary embodiment, includes, cell 15, anode basket 17 and cathode assembly 20. In general, anode basket 17 and cathode 20 are, in an exemplary embodiment, aligned and are, in an exemplary embodiment, within cell 15. Anode basket 17 suitably comprises any device in accordance with the present invention capable of holding a positive voltage potential and allowing metal ions to be liberated from metal pieces contained therein. In accordance with an exemplary embodiment of the present invention, anode basket 17 comprises a titanium basket substantially filled with raw nickel pellets.
With continued reference to FIG. 1, [0029] cathode assembly 20 suitably comprises any device in accordance with the present invention capable of holding a negative electrical potential and attracting ions at a rate which is proportional to the voltage potential across anode 17 and cathode 20 for a given resistance between anode 17 and cathode 20. In accordance with an exemplary embodiment of the present invention, cathode assembly 20 comprises a rotatable head 22 mechanically attached to an adjustable screw 24 and slides upon rails 23. Backplate 40 is, in an exemplary embodiment, attached to the opposite end of head 22. Rotatable head 22, in an exemplary embodiment, rotates at approximately 0-90 rpm.
With reference to FIGS. 1 and 2, [0030] cathode assembly 20 is suitably translated along the axis perpendicular to anode basket 17. More particularly, entire cathode assembly 20 head is suitably mounted on lead screw 24 and rails 23 which, when manually turned at hexagonal bolt head 25, in an exemplary embodiment, moves cathode assembly 20 in or out along rails 23 in relation to anode basket 17. In an exemplary embodiment, the total travel of cathode assembly 20 along rails 23 is approximately two inches thereby providing sufficient adjustment to greatly vary the thickness uniformity of the stamper. Furthermore, once adjusted, the positioning of lead screw 24 is suitably highly repeatable, such that the dimension and quality of the parts are highly predictable, thereby increasing productivity.
With reference to FIGS. 1 and 2, in an exemplary embodiment, [0031] lead screw 24 is suitably manually rotated at hexagonal bolt head 25. In an alternative embodiment, lead screw 24 is suitably driven by servo motor 26 which is suitably controlled by computer 28. Computer 28 suitably monitors the voltage and current in electroforming cell 15 and adjusts lead screw 24 accordingly. Thus, cathode 20-to-anode 17 distance is alternatively dynamically controlled with feedback from the voltage/current ratio across and through electroforming cell 15. In an alternative embodiment, computer 28 suitably compensates for the feedback from the voltage/current ratio for the complex changes which take place due to anode 17 material geometric irregularities and flow patterns and micro temperature variations within electroforming cell 15.
With reference to FIGS. 3 and 4, [0032] backplate 40 suitably comprises any device in accordance with the present invention capable of holding a part to be plated. In accordance with an exemplary embodiment of the present invention, backplate 40 includes a substantially circular disc with a front side 41 and a rear side 43. Backplate 40, in an exemplary embodiment, includes a clamping ring 42, a base 46, a metallic cup 48, three buttons 50, O-rings 52 and three recesses 54 substantially equally spaced about backplate 40. In an exemplary embodiment, base 46 and a metallic cup 48 are substantially circular discs. Base 46 and metallic cup 48, in an exemplary embodiment, include a rim emanating along their circumference toward front side 41. Metallic cup 48 is comprised of any suitable material capable of conducting electricity, but, in an exemplary embodiment, is comprised of a metal. Metallic cup 48 is, in an exemplary embodiment, reciprocally received in front side 41 of base 46, while master 90 is reciprocally received into front side 41 of metallic cup 48. Buttons 50 are, in an exemplary embodiment, substantially equally spaced substantially near the center of backplate 40. Buttons 50 are reciprocally received through base 46 and metallic cup 48 and abuts rear side 43 of master 90, such that when force is applied on rear side 43 of buttons 50, master 90 is forced away from front side 41 of backplate 40.
With reference to FIG. 3, to prevent fixture leakage and to reduce maintenance requirements, clamping [0033] ring 42, in an exemplary embodiment, includes a substantially circular ring comprised substantially of a rigid material, i.e. metal, ceramic, and/or the like. Clamping ring 42 is, in an exemplary embodiment, comprised of stainless steel, but clamping ring 42 is alternatively comprised of any suitable metal which is comparatively rigid such as aluminum, titanium and/or ordinary steel. Unlike plastic clamps, the properties of a stainless steel clamp also often enable repeatable compression and contact pressure. Clamping ring 42 suitably provides for a uniform compression of O-rings 52 thereby sealing off the metallic contacts of electroforming device 10. Any of the aforementioned metallic surfaces would normally contaminate the solution within cell 15; however, the metallic surfaces are suitably coated with a non-metallic surface which avoids contact with the plating solution. To avoid plating of clamping ring 42, clamping ring 42 is, in an exemplary embodiment, coated almost completely with a suitable substantially non-conductive, substantially non-chipping, extremely thin material. The non-conductive material is not only, in an exemplary embodiment, chemically compatible with the plating bath, but also suitably bonds to the metallic part and resists abrasion. The coating is suitably thin so as to avoid substantially increasing the dimensions of clamping ring 42. Coating of the metallic parts substantially improves the electroforming process by reducing unwanted plating to the fixture.
Prior art clamping rings typically are partially or completely removed from the fixture before loading or unloading the desired part. This process is often cumbersome, time consuming and adds to the risk of damaging the glass master or metal parts. In an exemplary embodiment of the present invention, due to the strength of the stainless steel, a [0034] hinge device 60 is suitably attached between clamping ring 42 and backplate 40 to allow rotation of clamping ring 42. Rotation of clamping ring 42 allows an operator to quickly load or unload parts because of the ease and quickness in opening and closing of backplate 40.
More particularly, with continued reference to FIG. 3, clamping [0035] ring 42, in an exemplary embodiment, includes hinge device 60 which is pivotally attached to base 46 along a predetermined length of front side 41 of backplate 40. Clamping ring 42 a plurality of virtually identical locking devices 62 substantially equally spaced about clamping ring 42. In an exemplary embodiment, clamping ring 42, in an exemplary embodiment, includes three locking devices 62. Each locking device 62 consists of a dowel 64 having a first end 65 and a second end 66. First end 65 of dowel 64 is suitably attached to hinge 68 which is mounted on a predetermined point on clamping ring 42. Second end 66 of dowel 64 is suitably attached to an object with a wider diameter than dowel 64, i.e. sphere 70. Upon rotation of hinge device 60 of clamping ring 42, clamping ring 42 abuts backplate 40. By rotation of locking devices 62 into recesses 54, dowels 64 are, in an exemplary embodiment, reciprocally received into recesses 54 and spheres 70 rest upon rear side 43 of backplate 40 and on ridge of base 46, thereby providing pressure between clamping ring 42 and front side 41 of backplate 40.
With reference to FIGS. 3 and 4[0036] a-c, O-rings 52 are, in an exemplary embodiment, set within circular channels of contact ring 80, base 46 and plastic holder 86. O-rings 52 provide an increased seal by substantially preventing the plating solution from exiting the cup area and attaching to electroplating device 10.
FIG. 4[0037] a shows an exemplary backplate 40 for creating a “father”94 from a glass master 90. With reference to FIG. 4a, contact ring 80 suitably comprises any device in accordance with the present invention capable of transferring current to the metallic surface on the front side 41 of glass master 90. In accordance with an exemplary embodiment of the present invention, contact ring 80 includes a conducting material such as stainless steel and/or the like. Contact ring 80 is, in an exemplary embodiment, set below rear side 43 of clamping ring 42, reciprocally received within the rim of base 46, over front side 41 of the rim of metallic cup 48 and over the outer circumference of master 90. Additionally, contact ring 80 helps prevent the plating solution from seeping out from the surface of master 90 and onto electroforming device 10, thereby substantially limiting the region of plating to the metalized glass. Because contact ring 80 covers the outer circumference of master 90, contact ring 80 oftentimes becomes plated to master 90, thereby essentially becoming a part of the resulting stamper/father 94. After removing stamper/father 94 from backplate 40, contact ring 80 is typically separated from father 94 by a suitable means.
In an exemplary embodiment, [0038] contact ring 80 includes a device for increasing the pressure of the contact ring against backplate 40. In one embodiment, and as shown in FIG. 11, a device for increasing pressure of the contact ring against backplate 40 includes a spring element. In a specific embodiment, spring element 140 may include a component 145 (e.g., rectangular component) cut out of the ring (e.g., on the outer circumference) at certain intervals, wherein component 145 is bendably attached to the contact ring 80 on one edge. In this manner, component 145 forms a resilient extension of contact ring 80 such that component 145 exerts pressure against backplate 40.
With reference to FIG. 5, when clamping [0039] ring 42 exerts pressure against contact ring 80, the rear surface 43 of contact ring 80 oftentimes experiences an uneven force, i.e. bending, against metallic cup 48 and master 90. To allow contact ring 80 to substantially evenly abut front side of the rim of metallic cup 48 and the outer circumference of master 90, a recess 81 is incorporated into rear surface 43 of contact ring 80 such, that contact ring 80 does not contact interface area between metallic cup 48 and master 90.
With continued reference to FIG. 5, rear [0040] 43, inner 83 surface of contact ring 80 includes beveled edge 82. Inner surface 83 of contact ring 80, excluding beveled edge 82, is also, in an exemplary embodiment, coated with a suitable non-conductive material which substantially prevents plating against inner surface 83 of contact ring 80. Consequently, beveled edge 82 abuts master 90, so when plating is deposited around the circumference of master 90, beveled edge causes a defined perimeter along the edge of the deposit. The defined sloping edge of the deposit allows substantially easier separation of master 90 from contact ring 80. Beveled edge 82 also suitably allows plating on the thin metalized layer of master 90 along the area which electrically contacts contact ring 80, thereby preventing the burning of the metalized layer during increases of current through the metalized layer.
FIG. 4[0041] b shows an exemplary backplate 40 for creating a “mother”98 from a “father”94. Electrical contact for metal-to-metal parts is typically initiated from the back of the part because the entire part, including the back surface, is conductive. With reference to FIG. 4b, the components of backplate 40 are, in an exemplary embodiment, arranged substantially similar to FIG. 4a except that, because the arrangement is, in an exemplary embodiment, established for creating mother 98 from father 94, father 94 is suitably comprised of a conductive metal so contact ring 80 is not necessary for transferring current to front side 41 of father 94. Instead, spacer 84 is, in an exemplary embodiment, reciprocally received within metallic cup 48 in place of master 90 and father 94 is, in an exemplary embodiment, set on front side 41 of spacer 84. In accordance with an exemplary embodiment of the present invention, spacer 84 includes a circular disc comprised of stainless steel or any other suitable conductive alloy.
Additionally, [0042] plastic holder 86 is, in an exemplary embodiment, an L-shaped circular ring including a foot 87 and a base 88. Base 88 of plastic holder 86 is, in an exemplary embodiment, set below rear side 43 of clamping ring 42 and foot 87 wraps around inside edge of clamping ring 42. Rear side 43 of base 88 is also, in an exemplary embodiment, set over front side 41 of rim of metallic cup 48 and over the outer circumference of father 94 and stainless steel spacer 84. A finger 89, in an exemplary embodiment, emanates from rear side 43 of foot 87 and substantially along the entire circumference of foot 87. Finger 89 is, in an exemplary embodiment, reciprocally received into one of two circular channels 85 within front side 41 of spacer 84, thereby enabling easy location and stable support for placement father 94. By using a rear entrance for the electrical contact (from metallic cup 48 through spacer 84 to father 94), electroforming device 10 is substantially sealed off from the plating material during the plating process. Thus, the plating material is substantially restricted from contact with electroforming device 10 and maintenance requirements are substantially reduced because of the reduced build-up of metal on electroforming device 10.
FIG. 4[0043] c shows an exemplary backplate 40 for creating a stamper (not shown) from “mother”98. With reference to FIG. 4c, the components of backplate 40 are arranged substantially similar to FIG. 4b except that mother 98, in an exemplary embodiment, replaces father 94. Additionally, plastic spacer 86, in an exemplary embodiment, includes a longer base 88 such that finger 89 of plastic spacer 86 is reciprocally received into inner circular channel 85 (closer to the center of stainless steel spacer 84 because mother 98 has a smaller diameter) of stainless steel spacer 84 thereby enabling easy location and stable support for placement of father 94.
As discussed above, because the nickel anodes are typically continuously corroding within the anode basket, it is important to sufficiently pack and clean the anodes to maintain optimal thickness variation. If the anodes are not sufficiently packed and cleaned, voids and sludge build-up within the basket may have an adverse effect on the thickness variation due to the effect on the electrical field. In one embodiment of the present invention, and as more fully disclosed in FIG. 6, the location of the cathode and anode are exchanged. The anode basket is configured as a disc which can be filled with anodes. The cathodic master is mounted stationary and parallel to the cathode. The anode basket rotates thereby providing similar benefits of agitation and relative motion, but with the additional benefit keeping the anodes sufficiently packed throughout the process. Further, the sludge is suitably cleaned during the process by the combination of rotation and flow. As such, the system is a substantially self-packing and self-cleaning system. Other alternative embodiments include rotating both the anode basket and the cathode relative to each other, alternating rotation of the anode basket and cathode relative to each other, simultaneously rotating the anode basket and cathode relative to each other and/or the like. [0044]
An alternative embodiment, as shown in FIG. 7, includes mechanically vibrating or otherwise agitating the stationary or rotating anode basket using, for example, a [0045] vibrator motor 100 which interfaces with the anode basket, to further pack and clean the anodes during the process. By substantially constantly packing and cleaning the anodes, the system provides repeatable thickness uniformity of the nickel stamper or shim. The mechanical vibration may range in frequency and power depending upon the size and shape of the anode basket and plating cell. For example, ultrasonic frequency ranges provide excellent cleaning as the sludge formed around the anodes is suitably broken up and carried off by the solution flow. By obtaining substantially clean and packed anodes, the electric field across the cathode is more uniform.
In another exemplary embodiment, the system and method includes any suitable hardware and/or software for reducing the variation or flattening out the electric field across the cathode, thereby allowing for better control of the thickness variation across the part. In one embodiment, as shown in FIGS. 8 and 9, the system includes a [0046] control grid 110 configured for reducing the variation or flattening out the electric field across the cathode 20. In another embodiment, at least a portion of the control grid includes a mesh, such as, for example, a mesh comprised of titanium. In one embodiment, the control grid 110 is disposed between the anode basket and cathode. In another embodiment, the control grid 110 is disposed between the anode basket 17 and a stationary cathode 20. Control grid 110 is disposed next to a device which is suitably configured to substantially filter at least a portion of sludge and substantially limit or restrict at least a portion of the sludge from adhering to the master. In one embodiment, the filter is polypropylene mesh 122. Polypropylene mesh 122 is disposed next to any suitable device configured for substantially focusing and controlling the flatness of at least a portion of the electrical current field that contacts the cathode. In one embodiment, baffle 124 substantially focuses and controls at least a portion of the flatness of the electrical field.
In another embodiment, the system further includes a circuit configured to distributing a bias current over [0047] control grid 110. As best shown in FIG. 10, in an exemplary embodiment, the negative end of power supply 115 is coupled to and provides a negative current to cathode plate 20. The positive end of power supply 115 is coupled to and provides a positive current to anode basket 17. The power supply 115 also is coupled to and provides a positive current to ammeter 117, which is coupled to resistor 120, which provides a positive current to titanium mesh 110, thereby allowing for adjustment of the bias current over titanium mesh 110 and monitoring the adjustments using the ampere readout on ammeter 117. In one embodiment, the currents are in the 1-2 ampere range which is small compared to the current in the electroplating bath. One skilled in the art will appreciate that the negative and positive ends of the power supply may be switched and the various components may be connected in series or parallel to provide the optimum circuit configuration for the various purposes of the present invention.
It will be apparent to those skilled in the art that the foregoing detailed description of an exemplary embodiment of the present invention is representative of an apparatus and method for a continuously manually [0048] adjustable anode 17/cathode assembly 20 distance and a hinged, coated, metallic clamping mechanism within the scope and spirit of the present invention. Further, those skilled in the art will recognize that various changes and modifications may be made without departing from the true spirit and scope of the present invention. For example, screw 24 used to continuously adjust cathode assembly 20 may suitably be replaced with any configuration capable of adjusting cathode 20/anode 17 distance. Those skilled in the art will recognize that the invention is not limited to the specifics as shown here, but is claimed in any form or modification falling within the scope of the appended claims. For that reason, the scope of the present invention is set forth in the following claims.

Claims

1. An apparatus for facilitating the uniformity of deposition in an electroforming process, wherein said apparatus includes an anode basket, a cathode facing said anode and a control grid between said anode and cathode, wherein said control grid is configured to substantially reduce the variation in the electric field across said cathode:

2. The apparatus of claim 1, wherein at least a portion of said control grid is comprised of a titanium mesh.

3. The apparatus of claim 1, wherein a polypropylene mesh is disposed between said control grid and said cathode, wherein said polypropylene mesh is configured to substantially filter at least a portion of sludge and substantially restrict at least a portion of said sludge from adhering to said cathode.

4. The apparatus of claim 1, wherein a baffle is disposed between said control grid and said cathode, wherein said baffle is configured for substantially focusing and controlling the flatness of at least a portion of an electrical current field that contacts said cathode.

5. The apparatus of claim 1, further including a circuit which is configured to distribute a bias current over said control grid.

6. The apparatus of claim 5, wherein said circuit includes a power supply, an ammeter, a resistor, wherein said power supply is coupled to said cathode and said anode and said power supply is further coupled to said ammeter, which is coupled to said resistor, thereby allowing for adjustment of said bias current over said control grid and monitoring adjustments using said ammeter.

7. An apparatus for controlling the uniformity of deposition in an electroforming process, said apparatus including an anode, a cathode assembly facing said anode, said cathode assembly comprising a backplate having a contact ring, said contact ring includes a device configured to increase the pressure of said contact ring against said backplate.

8. The apparatus of claim 7, wherein said device configured to increase the pressure of said contact ring against said backplate includes a spring element.

9. An apparatus for facilitating the uniformity of deposition in an electroforming process, wherein said apparatus includes a rotating anode and at least one of a stationary cathode and a rotating cathode facing said anode.

10. An apparatus for facilitating the uniformity of deposition in an electroforming process, wherein said apparatus includes an anode basket, a cathode facing said anode and an agitating device which is configured to provide agitation to said anode basket.

11. The apparatus of claim 10, wherein said agitating device includes a vibrator motor configured to provide vibration in the ultrasonic frequency range.

12. An apparatus for facilitating the uniformity of deposition in an electroforming process, wherein said apparatus includes:

an anode;

a cathode facing said anode;

an agitating device which is configured to provide agitation to said anode basket;

a control grid between said anode and cathode, wherein said control grid is configured to substantially reduce the variation in the electric field across said cathode, said control grid coupled to a circuit which is configured to distribute a bias current over said control grid; and,

said cathode comprising a backplate having a contact ring, said contact ring includes a device configured to increase the pressure of said contact ring against said backplate.

13. The apparatus of claim 12 further including said cathode being mounted on a lead screw for providing axial movement of said cathode along an axis normal to said anode to facilitate uniform deposition by optimizing said distance to compensate for factors affecting the uniformity of said electroforming process.

14. The apparatus of claim 13 further comprising a servo motor operatively connected to said lead screw, said servo motor communicating with a computer, said computer being adapted to control said axial movement of said cathode assembly.

15. The apparatus of claim 12 further including:

said backplate having a base with a recess which holds a metallic cup;

said metallic cup configured for holding a mandrel having a front face to be plated;

said clamping ring pivotally attached to said backplate, said clamping ring configured to hold said mandrel against said backplate; and

a contact ring within said backplate, said contact ring configured to transfer current to said mandrel, said contact ring adapted to abut the front face of said mandrel.

16. The apparatus of claim 12, wherein said base has at least one O-ring between said base and said clamping ring, said O-ring attached to said backplate and configured to impede the migration of processing solution between said clamping ring and said base.

17. The apparatus of claim 12, wherein said clamping ring includes at least one locking device for providing pressure between said clamping ring and said backplate.

18. The apparatus of claim 12, wherein said contact ring includes a beveled inner rim adjacent said front face of said mandrel to simplify separation of said contact ring from said mandrel.